The action of magnetic fields on flowing water is already known to activate water so that it can prevent lime deposits on metal surfaces and even remove existing lime deposits therefrom. It is assumed that this effect is due to the fact that magnetic action exerted on flowing water produces a small number of "activated" centers which act as crystal seeds on which lime is separated, mainly in a finely granular form, and then remains dispersed. The effectiveness of the activated centers remains preserved over a certain period, 48 hours at the longest. It appears that protection of metal surfaces against corrosion is maintained by the "activated" water forming a thin protective film of lime, while the formation of limestone is prevented or existing encrustations removed. This physical treatment of the water is performed without chemical additives, but requires a careful mutual adaptation of the quantity of water flowing through and the number, arrangement and strength of the magnetic fields acting thereon. The process and an apparatus suitable for its performance are disclosed, for example, in German Utility Model 89 13 274. In such a device water flowing spirally in a tube is subjected to magnetic fields. It should be noted that a magnetic fluid treatment device such as disclosed in the above-mentioned German Utility Model is also similar to the one disclosed in FIG. 4 of U.S. Pat. No. 4,512,289 (Collins). Also, a magnetic water treatment device is commercially available and is manufactured under the trade name "Permasolvent" sold by the firm Perma-Trade GmbH.
A suitable device for providing a magnetic action on a fluid is shown in FIGS. 10-14b. The permanent-magnetic liquid-treatment device, illustrated in FIG. 10 in a longitudinal cross-section, serves the treatment of water and is equipped with a para-magnetic tubular housing 101 which is flowed through from left to right by the liquid to be treated. At both ends 105 and 106 of the housing, which is illustrated in FIG. 11 again in a longitudinal cross-sectional view without inserts, connecting pieces 107, 108, of which one is illustrated in FIG. 12a in a longitudinal cross-section, are bolted by an external thread 128 to an internal thread 129 of the housing 101 and tightly joined by washers 126 which are seated in annular grooves 127 on the inside wall 116 of the housing 101. In the housing 101 is placed, coaxially to its longitudinal axis 110 and at a distance from its inside wall 116, a plastic internal pipe 102, which ducts the water to be treated through the housing and the two ends of which 117, 118 are connected in a leakproof manner to the connecting pieces 107, 108 by way of sealing rings 125 which are seated in annular grooves 124 of the connecting pieces, and the aforementioned internal tube ends are seated on a shoulder 123 of a respective connecting piece and are axially clamped to the housing 101 when the connecting pieces 107, 108 are bolted together.
The through-flow cross-section of the connecting pieces 107, 108 expands in the direction of the housing ends 105, 106. These conical expansions 113, 114, which are shown in FIGS. 12a and 12b, are at the inner ends, i.e. in the area of the annular groove 123 of the connecting pieces, matched to the throughflow cross-section of the internal pipe 102, i.e. they merge directly into the latter cross-section whilst the outer ends of these conical expansions merge into cylindrically formed threaded pieces 119, 120, by means of which not illustrated portions of a pipeline, into which the device is built, are bolted.
The internal pipe 102 has a smooth wall on its inside, i.e. it is not provided with chicanes, and is centrically to the centre axis 110 pulled through by an iron spindle 115 which intrudes into the connecting pieces 107, 108. The upstream end of this spindle, the diameter of which is small by comparison with the diameter of the internal pipe 102 so as not to excessively constrict the throughflow cross-section of the internal pipe, is seated in a bore 30 of the screwshaped conveying device 109 which is designed as a double-path screw, as can be seen in FIGS. 13a and 13b, and seated in the conical expansion 113 of the connecting piece 107, so that the diameter of the screw paths is matched to this conical expansion, as is shown in the drawing.
The other end of the spindle 115, i.e. the downstream end within the connecting piece 108, is seated in a plateshaped centring device 111, 112 which is illustrated in FIGS. 14a and 14b, i.e. in a bore 132 of the hub 111 of this centring device which is surrounded by a centring disc 112 which is seated on the conical expansion 114, as is shown in FIG. 10, and which is provided with two large water throughflow openings 131 as is shown in FIG. 14b, located on both sides of the hub 11.
In the annular space, which is located between the internal pipe 102 and the tubular housing 101 and sealed in a leakproof manner at the end by the aforementioned seals 125 and 126 and the inner ends 121, 122 of the connecting pieces 107, 108, are arranged in series in the direction of the longitudinal axis 110 of the housing annular magnets 103 and spacers 104, and the annular magnets 103 are axially magnetized and placed in respective pairs in antipole fashion, as is indicated in the drawing by pole markings. Two successive pairs of annular magnets are then separated from each other by a spacer ring 104 which is an iron pole-shoe. These annular magnets and spacer rings are seated on the internal pipe and generate magnetic fields which are oriented predominantly at right angles to the spiralshaped flow of water which passes through the internal pipe 102. The spiralling water flow is caused by the double-path screw of the device 109 in the upstream connecting pieces of the device, and water flowing in the direction of the internal pipe 102 is accelerated due to its conical narrowing 113, so that the device is suitable for the treatment of both relatively small and relatively large volumes of water. It has been found that the desired water treatment results are already achieved with volumes of water of approximately 0.5 l/min, and equally so for larger throughflow volumes of up to 60 l/min and above. These treatment results relate to scale precipitation as well as formation of a protective layer in the internal pipe and removal of old incrustations in the attached pipe system as well as a reduction of pipe corrosion and consequently a saving in washing materials as well as favorable biological effects.
The double-path screw is an essential feature of the inventive device, as it directs, with only low loss of pressure, inflowing water essentially independently of the throughflow volumes at virtually the same angle through the internal pipe around the spindle 115, so that the total length of the spirally ducted waterflow is a multiple of the length of the internal pipe. This achieves over a relatively short path or length of the internal pipe, in an experimental model 184 mm, a great number of intersecting points between the waterflow and the magnetic fields, some of which move semi-circularly from one iron pole-shoe 104 to the other, and others are ducted directly to the spindle 115. The degree of efficiency in the treatment of water of this device is respectively high. The aforementioned experimental model of the inventive treatment device has a total length of 300 mm and an outside diameter of 54 mm, an internal pipe inside diameter of 19 mm, an outside throughflow diameter of the connecting pieces of 133, 5 mm which is reduced by the conical narrowings on the internal pipe diameter. This device is equipped with 14 powerful annular magnets according to the arrangement illustrated in FIG. 1 and with 8 spacer rings which concentrate the magnetic fields of the annular magnets arranged after the first and last spacer ring onto the centre of the iron pole-shoes. In this case, 8 magnetic fields are ducted by the ferrous spindle onto the spindle, and additional magnetic fields move semicircularly from one spacer ring in the form of an iron pole-shoe to the other.
In practice it has been found that although this prior art process is basically usable, it often fails to produce the required results to an adequate extent--i.e., more particularly it often only inadequately prevents or removes lime deposits. The invention is intended to obviate this disadvantage. It is based on the discovery that to achieve success the water, after being adequately activated by the magnetic treatment, must achieve participation in sufficiently intensive contact with the surfaces to be protected against, or freed from, lime deposits.